Dosing of small pigment quantities

Figure: H. Scholz

Sketch of the Exacdos dosing system for small quantities, with enlargement of details

Figure: H. Scholz

Typical course of a saturation curve. Fluctuations in areas of slight increases in pigment dosing result in clearly visible differences in color intensity (see enlargement of the image detail on the left). When larger amounts of pigments are dosed, fluctuations in pigment dosing are barely visible (see enlargement of the image detail on the right)

Figure: H. Scholz

This figure illustrates the influence by the color of the sand on the color of the hardened concrete: both blocks were colored with Scholz Cobalt Blue G2727. The yellow color of the sand (right), together with the blue color of the pigment, results in giving the paving block a greenish color

Figure: H. Scholz

Manufacturers of cast stone slabs use small amounts of pigments per year. These are often weighed manually. This article points out the undesirable consequences this may have and ways to ensure uniform high color quality for end products.

Manufacturers of cast stone slabs have been using pigments – for example, Bayferrox iron oxide pigments – for coloring their products for many decades. In most cases, the amount of pigment used is slight, compared to the quantities employed by manu-facturers of concrete roofing tiles and concrete block pavers. This applies both to the amounts of pigment used per concrete mix and to annual pigment consumption. The reasons for such small consumption are as follows:

Small concrete mixers: For the production sequences in the manufacture of cast stone slabs, small quantities of facing mix are...